Therefore, it's unlikely that they will be healthy enough to participate in the Raiders first practice at training camp in Napa on Friday.

The designation means Hayden and Watson suffered injuries unrelated to football. Hayden and Watson can come off the list at any time during training camp and pick up where they left off, once they pass a physical.

There's no word on the nature or severity of Watson's injury. Raiders coach Dennis Allen is slated to speak with the media Friday for the first time since the conclusion of offseason workouts in June.

Hayden has been recovering from surgery to remove scar tissue in his abdominal region. He first had surgery in that area last November, when he suffered a ruptured vein. After the second surgery, Allen said he was confident that Hayden would be healthy enough to be on the field for the start of training camp.

Hayden signed a contract Thursday morning. Watson signed Wednesday. They were the first two players selected by the Raiders in the NFL draft in April. Hayden was the No. 12 pick.